we get the story tonight from nbc's chief science correspondent robert bazell. >> reporter: jake is a perfectly normal 16 years old but when he was 2 years old, shown on in these videotapes, he was diagnosed with severe autism, the widespread disorder that affects a child's ability to have social interactions. >> he stopped relating. he wasn't interested in other kids, and by his second birthday he stopped speaking entirely. >> reporter: after two years of intensive therapy 40 hours a week, he was declared free of autism, and he remains so to this day. >> when i look at the videos when i'm 2 years old, i cannot believe that at one point in my life that was me. >> reporter: new research from the university of connecticut closely studying 34 such cases including jake includes the outcome is real. therapy does bring a cure in some cases, and it is often with kids who were severely autistic. >> they had very little language when they were 2 and 3 years old, and they were really, most of them classically autistic. >> reporter: but the good news comes with caveats. researchers caution such